The state-of-the-art, storable bipropulsion system uses a hydrazine (typically monomethylhydrazine) as a fuel component. This fuel affords useful performance characteristics and has a fast ignition with an oxidizer. Such fast (hypergolic) ignition provides system reliability for on-demand action of the propulsion system. In addition, a bipropellant's hypergolic character is very beneficial since it removes the requirement of a separate ignition component; additional components bring increased inert mass and reduced system performance. The energy density of the state-of-the-art, storable bipropulsion system is largely limited by the density of the fuel. Storable fuels range in density from 0.88 g/cc (monomethylhydrazine) to 1.00 g/cc (hydrazine). Energetic ionic liquids have established densities that range well above 1.00 g/cc, and thus can confer greater energy density as bipropellant fuels. Also, there are significant costs and operational constraints associated with handling state-of-the-art fuels (hydrazines) that derive from the fuel's carcinogenic vapor. Fuel transport, loading and unloading are significantly complicated by its vapor toxicity and can require considerable efforts and costs in vapor monitoring with trained operations crews employed in expensive personal protection equipment.
Accordingly there is need and market for environmentally enhanced “green” fuels, which overcome the above prior art shortcomings.